[ Basic Info | User Guide ]
Basic Information on blflag
Purpose: Interactive flagging task.
Categories: uv analysis
BLFLAG is a Miriad task for flagging visibilities interactively.
It plots visibilities (e.g. amplitude vs time), either one
baseline at a time or all together, and allows discrepant points
to be flagged with a cursor.
Commands are entered as a single character at the keyboard:
Left-Button Left mouse button flags the nearest visibility.
Right-Button Right mouse button causes BLFLAG to precede to
the next baseline.
<CR> Carriage-return gives help.
a Flag nearest visibility (same as left mouse
c Clear the flagging for this baseline and redraw
h Give help (same as carriage return).
p Define a polygonal region, and flag visibilities
within this region. Define the vertices of the
polygon by moving the cursor and then hitting the
left mouse button (or a). Finish defining the
polygon by hitting the right mouse button (or x).
You can delete vertices with the middle mouse
button (or d).
q Abort completely. This does not apply flagging.
r Redraw plot.
x Move to next baseline (same as right mouse
z Zoom in. You follow this by clicking the mouse
on the left and right limits to zoom.
Input visibility dataset to be flagged. No default.
The normal Miriad linetype specification. BLFLAG averages all
channels together before displaying them, flags being applied
to all channels. The default is all channels.
Normal PGPLOT plot device. An interactive device, e.g. /xserve,
must be selected. No default.
Normal Stokes/polarisation parameter selection. The default is
'ii' (i.e. Stokes-I assuming the source is unpolarised). NOTE
BLFLAG plots the average of all the selected Stokes/polarisation
quantities. Also it flags ALL quantities, regardless of whether
they were selected or not.
Normal visibility data selection. Only selected data can be
flagged. The default is to select all data.
Two character strings, giving the X and Y axes of the plot.
Possible axis values are:
time (the default for the X axis)
lst Local apparent sidereal time.
hangle (hour angle)
channel (implies nofqav)
amplitude (the default for the Y axis)
rms Theoretical rms noise.
Plot range in the x-direction
If axis = uvdistance [kilo-lambda; 2 values]
If axis = time [dd,hh,mm,ss.s; 8 values]
If axis = amplitude, real, imag [natural units; 2 values]
If axis = phase [degrees; 2 values]
If axis = hangle [hh,mm,ss.s; 6 values]
If axis = rms [flux units; 2 values]
If axis = lst [decimal hours; 2 values]
For axis types other than 'time' or 'hangle', one or other of
the limits may be set with the other self-scaled by specifying
the lower limit as 'min' and the upper as 'max' (or simply
omitting it). For example,
self-scales the lower limit while pinning the upper limit to
zero, whereas either of the following
set the lower limit to zero while self-scaling the upper limit.
Default is to self-scale both limits.
Plot range for the y-axis as for the x-axis. The default is to
self-scale. For amplitude type plots you can greatly reduce the
number of points to plot by using something like yrange=0.3 to
cut out noise.
Task enrichment parameters. Several can be given, separated by
commas. Minimum match is used. Possible values are:
nobase Normally BLFLAG plots a single baseline at a time.
This option causes all baselines to be plotted on
a single plot.
selgen Generate a file appropriate for selecting the bad
data (via a select keyword). The output is a text
file called "blflag.select".
noapply Do not apply the flagging.
rms When processing spectra, blflag normally plots the
mean value of the spectra. Using options=rms causes
it to plot the rms value instead.
scalar When processing spectra, blflag normally forms an
average value by vector averaging. This option
causes it to generate the scalar average. It should
be used with significant caution.
nofqaver Do not average spectra - the resulting number of
points may be too large to handle. Use select to
break up the data in time ranges or use yrange to
The following options can be used to disable calibration.
nocal Do not apply antenna gain calibration.
nopass Do not apply bandpass correction.
nopol Do not apply polarisation leakage correction.
Revision: 1.22, 2015/12/04 03:07:29 UTC
Generated by email@example.com on 21 Jun 2016